This invention relates to the polymerization of alpha-olefins, and more particularly, to an improved, highly active and stereospecific catalyst for polymerization of alpha-olefins.
Our co-pending application Ser. No. 113,543, filed January 21, 1980 now U.S. Pat. No. 4,277,370, discloses highly active and stereospecific catalysts for alpha-olefin polymerization comprising (A) an organoaluminum component and (B) a stereospecific supported component prepared from (1) at least one halogen-containing compound of tetravalent titanium, (2) at least one organic electron donor, and (3) at least one magnesium-containing pretreatment product of components comprising (a) at least one magnesium alcoholate, (b) at least one metal alkyl compound of a metal of Group II or IIIA of the Periodic Table, and optionally, (c) at least one modifier component selected from the group consisting of mineral acids and anhydrides of sulfur, organometallic chalcognide derivatives of hydrogen sulfide, organic acids and organic acid esters. According to a preferred aspect of that application, the reaction product of the aforesaid components (1)-(3) is contacted with liquid Lewis acid to improve activity and stereospecificity.
Despite the desirable performance of the catalysts disclosed in the aforesaid application, improvements in polymerization performance, and particularly activity and/or stereospecificity, would be desirable. It is an object of this invention to provide such improvement. Further objects of the invention are to provide an improved alpha-olefin polymerization catalyst component and catalyst based thereon. Still further objects of the invention are to provide for the preparation of such improved catalyst components and catalysts as well as for the use thereof in the polymerization of alpha-olefins.
We have now found that the objects of this invention can be attained by treatment of the reaction product of the aforesaid components (1)-(3) with certain halogenated aliphatics. Advantageously, the resulting supported catalyst components, on combination with organoaluminum promoter, exhibit polymerization activities and/or stereospecificities at least comparable to those of the preferred catalysts disclosed in application Ser. No. 113,543. In addition, treatment with halogenated aliphatics according to the present invention offers advantages over the Lewis acid treatment of Ser. No. 113,543 in terms of cost and convenience.
Prior art proposals which may be of interest with respect to the present invention include Japanese Patent Publication No. 54-062,289 (Mitsubishi Chemical Ind.), which discloses the use of CCl.sub.4, CHCl.sub.3 and CH.sub.2 Cl.sub.2 as halogenating agents in preparation of supported, stereospecific catalyst components. Other materials employed in preparation of the catalyst components are alcohols, Grignard compounds, TiCl.sub.4 and electron donors. Various preparative sequences are disclosed, all involving the use of halogenating agent prior to reaction with TiCl.sub.4. In contrast, treatment with halogenated aliphatics according to the present invention takes place after reaction with titanium (IV) compound. The catalyst components disclosed in the cited publication also are different from those of the present invention in terms of starting materials and other preparative steps.
It also is known to employ various halogenated organic compounds as solvents in preparation of supported stereospecific catalyst compounds as evidenced by the following:
______________________________________ U.S. Pat. No. 4,069,169: methyl iodide, ethyl bromide, (Toyoda et al.) n-propyl chloride, methylene iodide, carbon tetrachloride, chloroform and chlorobenzene (Column 8 lines 20-25); U.S. Pat. No. 4,146,502: 1,2-dichloroethane, propyl (Yokoyama et al.) chloride, butyl chloride, chlorobenzene and bromobenzene (Column 5 lines 32-40); U.S. Pat. No. 4,180,636: methylene chloride, trichloro- (Hirota et al.) ethane, trichloroethylene and chlorobenzene (Column 11 lines 47-53); Japan 54-039,483: C.sub.1-12 halohydrocarbons; (Mitsubishi Petro- chemical Co.) Japan 54-131,589: 1,2-dichloroethane, butyl (Mitsubishi Petro- chloride, bromobenzene. chemical Co.) ______________________________________
However, the foregoing do not suggest treatment of supported catalyst components with halogenated aliphatics to improve polymerization performance. Further, none of the foregoing suggests the use of halogenated aliphatics in conjunction with the specific supported catalyst components employed according to this invention.
It also is known that halogenated aliphatics such as carbon tetrachloride can be employed in preparation of organoaluminum-reduced, electron donor complexed, unsupported titanium trichloride catalyst components. Thus, for example, U.S. Pat. No. 4,183,824 (Shiga et al.) discloses preparation of titanium trichloride-based catalyst components by reduction of titanium tetrachloride with an organoaluminum component followed by complexing the first step product with an ether, treatment of the resulting complex with certain organoaluminum halides in the presence of a halogenated organic compound, and treatment of the result with ether in combination with certain tertiary carbon-containing compounds and/or certain organosulfur compounds. Of course, the supported catalyst components of the present invention differ substantially from unsupported TiCl.sub.3 components such as those of Shiga et al. in terms of composition, manner of preparation and polymerization performance.